Current and Voltage Enhancement with Embedded Superlattices in Planar Series Connected p-i-n Cells
Argyrios C. Varonides · EU PVSEC · 2012
We propose deconstructing a vertical p-n/TJ//p-n double-cell device into a series connected twocell configuration with similar designs targeting both voltage increase and incident spectrum range widening. Photo-generated currents in the two p-n junctions form a continuous flow, while voltage enhancement occurs due to the series connection. Photo-excitation and (reduced) recombination occur independently in both cells which are designed for both visible and infrared absorption. Immediate advantages of the proposed geometry are: (a) voltage output increase due to series connection (as in regular MJ cells) (b) no photon shadowing effects (c) no need for tunnel junctions and (d) flexibility in connecting more than one units in an IC fashion (integrated photovoltaics. For two series connected AlGaAs/GaAs/Ge with short superlattices embedded in both, we predict voltage doubling with ideal current matching, and collection efficiency in excess of 44% (X=100 suns) and a collection effici3ncy in excess of 40%.